Código:
He probado con los conversores de developerfusion pero no funciona el cógido generado Dim oleApplication As Type = Type.GetTypeFromProgID("Word.Application")
Dim Application As Object = Activator.CreateInstance(oleApplication)
Application.Documents.Open(strpath)
Application.Run("AdobePDFMaker.AutoExec.ConvertToPDF")
Application.Documents.Close()
Application.Quit()

